The rate laws and mechanisms of key reactions of hemerythrin will be determined. These reactions include the oxygenation of deoxyhemerythrin, the autoxidation of oxyhemerythrin in the presence of anions, the oxidation of deoxy- and oxy-hemerythrin by iron(III) cyano and other complexes, and the reduction of methemerythrin derivatives by dithionite ion. These are important reactions either in the function or loss of functions of the respiratory protein in the marine worm Goldfingia gouldii or in the laboratory preparation of pure forms of the protein. All these reactions have parallelisms with globin chemistry, and comparisons will be sought.